1. Field
The present invention relates generally to a system comprising a broadcast channel and a data channel, and more specifically, but not exclusively, to a method and apparatus relating to validation and channel change in a digital video broadcast system using a broadcast channel and having a connection using a data channel.
2. Description of the Related Art
A terminal may be capable of receiving data services, for example video data services, using a broadcast channel such as a terrestrial, satellite or cable Digital Video Broadcasting (DVB) channel, and may also be capable of receiving data services such as Internet Protocol Television (IPTV) using a data channel, such as an internet connection through, for example, a telecommunication service, such as a fixed line or wireless link.
A validation process may typically be required to validate that a terminal is authorised to receive a data service before a terminal is enabled to receive the data service. Such validation processes are well developed for DVB services delivered using a broadcast channel.
In order to validate that a terminal is authorised to receive a data service using the data channel, a validation process may be used that is based on sending a token, using a data service over the broadcast channel, so that the token may only be received by terminals authorised to receive the data service using the broadcast channel. It may then be assumed that the terminal is also authorised to receive certain data services using the data channel, and this may be enabled as a result of the terminal sending a token that it has received using the broadcast channel to a server for a data service using the data channel. The server may then enable the terminal to receive the data service using the data channel if the token is identified as valid. Such a system has the disadvantage that the broadcast data service has to be modified to transmit the token, and equipment is required to generate the token.
A data service, and in particular a digital video service, may consist of a data stream that has designated access points, such as Random Access Points (RAP), from which it is possible to start receiving the data service. It may not be possible to start decoding the service starting from a point between the designated access points. For example, a designated access point may provide information necessary to decode a video frame, but between designated access points, only incremental information may be provided on the assumption that the frame has been received. As a result, for example when changing channels, there may be a delay before a channel can be decoded to provide a video signal.
It is an object of the invention to mitigate the problems with the prior art systems.